QUANTITATIVE VARIATION OF ECDYSTEROIDS OF IXODID TICKS

Abstract  In order to explore the role of ecdysteroids in development and reproduction of ixodid ticks, we studied the quantitative variation of ecdysteroids in the hemolymph, synganglion, ovary and whole body of the female ixodid ticks, Dermacentor niveus and Haemaphysalis longicornis , before and after engorgement and oviposition by HPLC and RIA. The ecdysteroid content in eggs of these ticks was determined by HPLC. The results indicated that before engorgement the quantitative variation of ecdysteroids in the whole female body was not significant, but their levels increased rapidly after engorgement. The ecdysteroid titer in hemolymph was peaked on the 5th day after engorgement, which was one day prior to oviposition. It may be regarded as a singnal of oviposition. In the synganglion the peak of ecdysteroid level occurred also on the 5th day after engorgement. This is coincident with the secretory activity of neurosecretory cells of synganglion. From the 3rd day after engorgement until oviposition the ecdysteroid level in the ovary increased rapidly. Ecdysteroids were detected in eggs of H. longicornis too. They stem from ovary and accumulated with the process of embryonic development.     

Immobilization of Lipase from Rhizopus Niveus: A Way to Enhance its Synthetic Activity in Organic Solvent

Lipase (EC 3.1.1.3) from Rhizopus niveus was immobilized by physical adsorption on various carriers, including different types of Celite, Spherosil and Duolite. After the enzyme immobilization, the recovered hydrolytic and synthetic activities on the different carriers were then determined. The results showed that the highest synthetic activity was obtained when Duolite XAD 761 was used as the carrier. However the recovered hydrolytic activity after the immobilization on this resin was relatively low although this carrier showed the best protein loading capacity. The highest recovered hydrolytic activity was observed when the lipase was immobilized on Celite Hyflo-Supercel using an immobilization buffer adjusted to pH 4. The comparison of the free and immobilized lipase specific activities suggest that the immobilization on Celite Hyflo-Supercel, Spherosil XOA 200 and silica has enhanced the lipase hydrolytic activity. On the other hand, the use of the lipase immobilized on Duolite XAD 761 as biocatalyst of synthetic reaction, compared to that of the free enzyme, allows the reaction initial velocity to be increased 12.2-fold. In addition, the synthetic activity of the lipase immobilized on Duolite XAD 761 was shown to be maximum at a water activity in the range of 0.32-0.52.     

THE ROLE OF ECDYSTEROIDS IN THE REPRODUCTIVE DIAPAUSE OF DERMACENTOR NIVEUS NEUMANN

Abstract  The ecdysteroid levels in hemolymph, ovary, synganglion and whole body of diapausing female Dermacentor niveus were detected by HPLC, and compared with the results of nondiapausing female. It is revealed that the ecdysteroid levels in hemolymph and ovary of diapausing female are similar basically to that of nondiapausing female in the first few days after engorgement. From the 10th day after engorgement, the ecdysteroid levels of diapausing female decreased and even became distinctly lower than that of nondiapausing female. The paucity of ecdysteroids in these individuals would influence the normal development of oocytes. In order to explore the effect of ecdyateroids on the diapausing female, we injected 20-hydroxyecdysone with different dosages at different time into the ticks, and found that after just complete engorgement the injection with large dosages (10000 and 1375 ng/tick) caused death of the ticks. From 10th to 20th day after engorgement the ecdysteroid levels of diapausing female are lower than that of nondiapausing one before oviposition, the injection with certain dosages 50, 70 and 100 ng/tick> of 20E can accelerate vitellogenesis and terminate reproductive diapause, but the amount of eggs produced by them is less than that produced by nondiapausing female. The termination of diapause in female of ixcdid tick by exogenous ecdysteroids is reported for the first time.     

QUANTITATIVE VARIATION OF 20-HYDROXYECDYSONE IN THE NYMPH OF DERMACENTOR NIVEUS NEUMANN*

Abstract The variation of 20-hydroxyecdysone (20 E) levels in the unfed, feeding and engorged nymphs of Dermacentor niveus was studied. The results showed that 20 E existed in all stages of nymphal development. There were two peaks. A small peak (2. 34 ng/nymph) appeared in the feeding period (5 days after attachment) which was connected with the fast feeding before dropping from the host, and a big peak (16.17 ng/nymph) in the moulting period (8 days after engorgement). The latter might be correlated with epicuticle deposition. From the 6th day to the 8th day after engorgement, the level of 20 E rose rapidly. Apolysis occurred in this period.     

Nucleotide sequence of the structural gene for the penicillin-binding protein 2 of Staphylococcus aureus and the presence of a homologous gene in other staphylococci

Abstract During growth of Streptomyces niveus wild-type in the novobiocin production medium CDM the resistance of mycelia to novobiocin rises from about 25 μg/ml to over 200 μg/ml. ( S. lividans , a novobiocin-sensitive strain, is resistant to approx. 10 μg/ml novobiocin.) The initial period of low level resistance extends from the time of inoculation of the culture until approx. 70 h when the culture is still in the growth phase. High level resistance is initiated before the start of novobiocin production and rises rapidly to a maximum level beyond the end of the growth phase. The rise in pH of the unbuffered CDM medium which occurs during S. niveus fermentation was shown not to be the cause of the change in novobiocin resistance. However, mycelia-free CDM from S. niveus cultures expressing high level novobiocin resistance was shown to contain a factor which induced high level novobiocin resistance in germinating S. niveus spores. Kinetic studies revealed that the inducer first appears in the culture medium before the switch to high level resistance begins and reaches its highest concentration before resistance reaches its maximum level.     

银盾革蜱若虫发育期20-羟基蜕皮酮含量变化规律(英语)

本文利用高效液相色谱(HPLC)对银盾革蜱饥饿、吸血和饱血后若虫整体水平20-羟基蜕皮酮含量变化规律进行了研究.结果表示20-羟基蜕皮酮存在于若虫整个发育期,其含量变化具有两个峰.第一个峰小,出现在吸血期(吸血后5天),含量为2.34ng/只,该峰出现后,若虫快速饱血并从宿主体落下;第二个峰大,出现在蜕化期(饱血后8天),含量为16.17ng/只,此峰可能与上表皮沉积有关.从饱血后第6天至饱血后第8天,20-羟基蜕皮酮含量迅速增加,皮层溶离发生在饱血后7天左右.     

Eradications and People: Lessons from the Plant Eradication Program in Galapagos

It is often argued that the benefit of eradication of an invasive species—a one-off injection of funds and the problem is solved—far outweighs the cost of a perennial control program. Furthermore, these are very attractive projects for funding agencies as outcomes are clear and easy to assess. Galapagos is in the early stage of the invasion process, with most alien species not yet naturalized and still restricted to gardens and farms. These species should be easy targets for early and cost-effective eradication projects, which would prevent many future problems. We review 30 plant eradication projects covering 23 potentially invasive species with limited distributions on four of the Galapagos Islands. Of the 30 projects, only four were successful: these were all less than 1 ha in net area, on land with a single owner and did not have persistent seed banks. Of the other 26 projects, most failed due to a lack of support from institutions that did not offer continuity of resources, from land owners who denied permission to carry out the work or from being too ambitious. As a result of these problems, 64.3% of the funding secured for the program was spent on discontinued projects. We highlight lessons learned to inform plant eradication programs in the future.     

Isolation and Identification of the Lipolytic and Thermophilic Fungus

In view point of the basic research for the enzyme properties and the development of utilization of lipase, a thermophilic fungus which could produce a remarkable amount of thermostable, alkalistable and extracellular lipase has been isolated from the compost soil. The taxonomical characteristics of this thermophilic fungus were examined and it was identified as Humicola lanuginosa S-38.     

硬蜱中蜕皮激素含量的变化(英语)

为阐明蜕皮激素在硬蜱发育和生殖中的作用,用高效液相色谱法(HPLC)和放射免疫测定法测定了银盾革蜱和长角血蜱中饱血和产卵前后雌虫整体、血淋巴、合神经节及卵巢中蜕皮激素含量的变化.此外,还用HPLC测定了长角血蜱的卵和幼虫中蜕皮激素的含量.结果表明:在饱血前雌虫整体中蜕皮激素含量的变化不大,饱血后迅速增加.血淋巴中的蜕皮激素在饱血后第5天(即产卵前1天)达到高峰,可做为产卵的信号.合神经节中蜕皮激素含量的高峰在饱血后第5天,与血淋巴中高峰出现的时间一致,这与神经分泌细胞的分泌活性变化相吻合.从饱血后第3天起,卵巢中蜕皮激素含量增加很快,直到产卵时止,在长角血蜱的卵中也测到α-蜕皮素,来源于卵巢,随胚胎发育进程其含量逐渐增加.卵产出后第4天到第12天,蜕皮激素的含量增加十几倍.     

3种蛾类雄性内生殖系统形态学研究

为了探究蛾类昆虫新的有效分类特征,本研究对直脉青尺蛾Geometra valida、白雪灯蛾Chionarctia niveus和多斑豹蠹蛾Zeuzera multistrigata雄性内生殖系统进行了解剖观察和形态学比较。结果表明：3种蛾类雄性内生殖系统均由精巢、贮精囊（前贮精囊和后贮精囊）、输精管、复射精管、单射精管（单射精管原节和单射精管表皮节）和附腺组成;种间形态差异表现在贮精囊的形状及连接方式、复射精管的形状及长短、单射精管和附腺的长度等方面,这些鉴别特征可为蛾类分类及系统发育研究提供形态学借鉴。